Die casting apparatus



Sept. 6, 1966 A. MADWED 3,270,378

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United States Patent C) 3,270,378 ElE CASTNG APPARATUS Albert Madwed, Bridgeport, Conn., assigner to Automatic Qasting Corporation, Bridgeport, Conn., a corporation of Connecticut Filed `lan. 16, 1964, Ser. No. 338,084 9 Claims. (Cl. 22-70) The present invention relates to apparatus for die casting and more particularly to improvements whereby the problems arising from the freezing of molten metal in the nozzle section of the injection device and/or the drippage of molten metal onto the die faces are avoided.

In my copending application Serial No. 198,916, tiled May 3l, 19612, now U.S. Patent No. 3,123,875, I have disclosed methods and apparatus providing for the rapid l withdrawal of the molten metal from the gooseneck and nozzle in the shortest possible time after the completion of the metal injecting operation to separate the solidifying metal in the xed die from the molten metal in the nozzle and adjacent part of the gooseneck and to maintain the withdrawal of the molten metal until the die pants have been separated thereby preventing the metal from solidifyin-g in the nozzle and clogging the same and avoiding the danger of molten metal from the sprue or nozzle dripping onto the faces of the die .parts and freezing thereon with the advantageous results therein described.

The present application is directed to a modification of the apparatus disclosed in my pending application above identiiied in which the apparatus is greatly simplilied and thus may be more economically manufactured and installed on existing die casting machines and more easily maintained.

The salient feature of this application is the provision of mechanical means for positively arresting the return movement of the shot plunger at a position in which the iill-port is maintained closed until the die parts are separated, and thereafter releasing the plunger-arresting means in response to the opening movement of the die parts.

In the speciiic form of the invention illustrated and described herein the pluntgerarresting means comprises an abutment means and latch means, the abutment means preferably being connected to the shot plunger while the latch means is connected to a iixed part of the frame of the mach-ine. Also in the p-resently preferred form the means for releasing the latch means in response to the movement of the movable die part comprises a pull rod connected to said die part and to the latch means to render the latter ineffective to prevent the final movement of the shot plunger and thus opening the fillport.

These and other objects and advantages of the present invention will be apparent to those skilled in the art in the light of the following description and the accompanying drawings in which:

FIGURE l is a side view of a part of an automatic die casting machine according to the invention showing the die parts separated and the shot plunger in its starting position.

FIG. 2 is a side view of a segment of the part of the machine illustrated by FIG. l and showing the molten metal injected into the die cavity, the shot plunger being fully operated.

FIG. 3 is a side view corresponding to FIG. 2 but illustrating the plunger arrested in partially retracted position during solidiicafion of the casting, the till-port remaining closed.

FIG. 4 is a side view of the parts shown in FIG. 2 but illustrating the shot plunger in fully retracted position and the dies having been separated prior to the opening 'of the till-port.

3,270,378 Patented Sept. 6, 1966 Mice FIG. 5 is a schematic view of the means for operating and controlling the operation of the shot plunger and the opening and closing of the die parts.

FIG. 6 is a fragmentary view showing gravity means for rendering the plungenarresting means operative.

FIG. 7 is a schematic view of a modied for-m of stopping means and the means for operating it.

For purposes of explanation, as illustrated by the drawings, the die casting machines comprise a furnace 1 having a heating chamber 2 andan opening 3 providing access for a gas flame or other heat-supplying means. Into the heating chamber is mounted a vat 4 for containing the casting metal 5 and maintaining it in molten condition. Though not essential to the operation of the present apparatus, the vat is preferably divided by a partition 6 to form a pot A and an auxiliary pot B, as illustrated. The level of the molten metal in pot A may, in the broader aspects of this invention, be maintained constant in any suitable manner, but preferably by means of a ladle 7 pivotally mounted on shaft 8 which is automatically operated as will be explained below. An arm 7a of the ladle 7 is operated by a pin and slot connection 9, 9a with an arm 10 mounted on shaft 1\1 adjustably secured to the movable die block frame 12 by means of nuts 13. Any excess molten metal added to the pot A by the ladle 7, or otherwise, overflows the partition 6 into the pot B.

Within the pot A is mounted a shot cylinder 15, the lower open end of which joins .a gooseneck 16, provided at its upper end with a discharge nozzle 17 communicating with the sprue hole 18 of the fixed die part 19 mounted on the frame 20 of the machine. A shot plunger 21 is slidably mounted within the cylinder 15 and is connected to .a rod 21a of an air cylinder 22 mounted on the top frame 20a of the machine. The upper end of the rod `21a ha-s mounted thereon piston 23 which is reciprocated in the cylinder 22 by means of air pressure alternately exerted and exhausted through supply lines 24 and 24a connected .to a distributing valve Z6, shown in FIG. 6.

When the plunger 2 1 is moved downwardly or on forward stroke be exerting air pressure in line 24 and exhausting through line 24a, it forces molten metal from the cylinder 15 through gooseneck section 16 and out of the nozzle 17 into the die cavity, as illustrated by FIG. 2. This step occurs only when the die parts are in engagement.

The movable die -part 27 is mounted on the die block 12 which has attached thereto suitable linkage mechanism represented by the ramrod 28 which has on the opposite end a piston 29 slidably mounted within a ram cylinder 30. The movable die 27 is moved towards and locked against the stationary die 19 by means of iluid pressure exerted in ram cylinder 30, driving the rod 28 and the die block. vThe die block and movable `die are kept in perfect alignment with the stationary ldie by means of rods 31 on which the die block 27 is slidably mounted by means of bearings 32.

Associated with the movable die 27 is a plate 33 having attached thereto knockout pins 34 and rods 35. When the movable die 27 is in engagement with the lixed die 19 the ejector plate 33 is in the position shown in FIGS. 2 to 4 and the knockout pins 34 are retracted so as to be flush with the surface of the movable die. When the casting operation is completed and the movable die 27 is retracted, as shown in 1, the ejector rods 35 make contact with ejector abutments shown at 39 in FIG. 1, compressing springs 36 and forcing the knockout pins against the casting and pushing it from the core member 37 on the movable die. When this occurs the casting falls away from the movable die 27.

The operation of the apparatus of this invention is similar to that of conventional die casting machines up 3 to a point. For instance, each casting cycle begins when the dies are separated or in open position and the shot plunger 21 is at the limit of its up position, as illustrated by FIG. 1.

Referring to FIG. 5, a cycle is lstarted when a casting made by the previous cycle is ejected onto a chute 414 and depresses a pivoted arm 45 to actuate a switch 46 to start the operation of a timer 47. The timer actuates a distributing valve 48 which in turn energizes piston 29 within the ram cylinder 30 by means of fluid pressure exerted through supply line 49 and exhausted through supply line 49a to drive the movable die against the fixed die. At the end of the forward motion of the movable die 27 a lug 12a on the die carrier 12 strikes a switch 51B and `starts a timer 51 associated with distributing the valve 26 for actuating the plunger 21. When lthe plunger moves down it rst closes off the fill-port 14a and then forces the molten 4metal in the shot cylinde-r 15 and gooseneck 16 into the nozzle 17 and then into the cavity of the die.

In conventional die casting methods as heretofore practiced, after the lapse of a predetermined time controlled by a timer such as the timer 51, the distributing valve 26 is actuated to cause fluid under pressure to return the plunger 21 to its starting position as shown in FIG. 1, but according to my invention as disclosed in my said copending application provision is made for rapidly returning the plunger 21, preferably as soon as sufficient time has elapsed after the injection of the molten metal into the dies for the gates and runners of the casting to solidify, then withdrawing the molten metal from the nozzle and from the upper portion of the gooseneck, and preventing return of the molten metal to the nozzle and sprue hole until the casting has solidified and the die parts have been separated.

In the form of my invention herein described and illustrated, the plunger 21 is prevented from returning immediately to its starting position .shown in FIG. l by positive acting mechanical means which as illustrated herein may comprise an abutment connected to the plunger 21 and a latch or blocking member mounted on a stationary part of the machine frame a.

As shown, the abutment comprises a disk 52 which for the convenience of installation and adjustment may be `rotatably mounted on a threaded portion S3 of an intermediate section 54 of the plunger operating rod 21a. The disk 52 is secured in desired location byv lock nuts 55.

The latch or blocking member as shown comprises an arm 56 pivotally mounted at 57 on the frame 20 and extending downwardly to a position shown in FIG. 2 where its lower end will strike the disk 52 and arrest the return movement of the plunger 21a at a determinate position. The lower end of the arm 56 may be provided with a roller 57 to reduce the friction between the arm `56 and the disk 52.

The arm 56 is of such length and the disk 52 is so positioned that when the ldisk is engaged by the arm to arrest the plunger -rod 21a as shown in FIG. 3, the bottom of the plunger 21 is adjacent but below the fill-port 14a thereby prevent the flowing of molten metal into the shot cylinder and the filling of the void left by the Withdrawal of the molten metal in the returning movement of the plunger.

According to my method of operation, this condition is maintained until the movable -die part 27 and casting have been separated from the fixed die part 19 which may occur as soon as the metal in the gates and runners of the die have solidified sufficiently to block reverse flow of metal from the article-forming cavities in the die parts.

As `shown herein, the arm 56 which prevents return of the plunger 21 to starting position is released from its blocking position by means operated by the opening movement of the movable die part. In the specific ernbodiment of my invention shown, this is accomplished by mechanically connecting the arm 56 to the holder 12 for the movable die part by a pull rod 58 pivot-ally i connected at 59 to the arm 56 and extending through a guide 641 in the upright 61 of the machine frame and through a hole in a lug 62 mounted on the die holder 12. The projecting end of the rod 5% is threaded and is provided with nuts 63 which engage the lug 62 during the opening movement of the movable die part and pull the arm 56 from its locking position shown in FIG. 3 to release the roller 57 from the disk and allow the disk 52 and plunger 21 to move upwardly. The nuts 63 are so adjusted on the pull rod 58 that they are engaged by the lug 62 only after the die part 27 has been moved far enough to withdraw the casting and the sprue from the fixed die part and before (as shown in FIG. 4) the movable die part reaches the end of its opening movement. The arm 56 is prevented from immediately relocking the plunger rod 21 by its engagement with the peripheral edge of the `disk 52 as shown in FIG. 4.

The piston 23 and plunger 21 are returned to starting position as shown in FIG. 1, in which the fill-port 14a is open and the molten metal fiows into the shot cylinder and up the gooseneck preparatory to the next casting operation, by the fluid pressure on the underside of the piston 23 which is maintained thereon until the reverse valve 26 is operated after the die parts are reclosed.

In the next casting operation, after the plunger 21 has descended, the arm 56 moves to the position shown in FIG. 2 ready to intercept the disk 52 on its return stroke. The arm 56 may be moved to the position shown in FIG. 2 by any suitable means, for instance by the spring 64 which is carried by the pull rod 58 interposed between the lug 62 and a collar 65 on the pull rod 58. When the die holder 12 is moved to die-closing position, the spring 6d is compressed to activate the rod 58 for the purpose stated.

In order to prevent the upward pressure on the arm 56 by the disk 52 from unintentionally releasing the arm from the disk, provision is made for moving the arm 56 to the right as shown in FIG. 2 beyond a perpendicular line passing through the pivot 57, and the collar 65' is positioned so as to engage the fixed guide 61 through which the rod extends when the arm 56 is in proper position.

If desired, thespring 64 may have substituted for it a weight such as the weight 65 shown in FIG. 6.

For the purposes of the present invention, the shot plunger 21 may be arrested in its return movement in a position where it still closes the fill-port 14a, by electromechanical means. As shown in FIG. 7, in which the various parts which are also found in FIG. 5 have applied to them the same reference numerals as in FIG. 5, this can be accomplished by providing the plunger 21 with a stop lug 112 positioned to be engaged by a stop latch 113 connected to the armature of a solenoid 114 and which is urged by a spring 115 to position to engage and arrest the upper movement of the rod 21a and plunger 21 before the bottom of the latter clears the fill-port 14a. When the movable die has separated from the fixed die, a switch 116, positioned to be engaged by a lug 12a on the movable die holder 12, is operated to close a circuit including wires 117 and 118 leading to the solenoid 114 which, upon being energized withdraws the latch 113 from the lug 112 thereby allowing the rod 21a and plunger 21 to move to the upper limit of its travel in which the fill-port 14a is open. In so doing, the lug 112 passes beyond the latch 113 and is positioned as shown in FIG. 7, by a spring 115.

When the next cycle of operations takes place and the timer 51 and distributing Valve 26 operate to apply pressure to the top of the piston 23, the stop latch 113 is cammed back because of the sloping surfaces of the latch and lug, and after the lug passes the latch, the spring 115 returns the latch to lug-intercepting position.

In this embodiment of the invention, the switch 116 needs to be operated only by the opening movements of the movable die holder 12, since the stop lug 112 freely passes the latch during the injection stroke of the plunger Z1. The switch 116 therefore is of the type which closes the circuit in only one direction of operation of its movement.

Variations and modifications may be made within the scope of the claims 4and portions of the impr-ovements may be used without others.

I claim:

1. In a die casting machine having separable die parts and means for moving said die parts to closed position to form a die cavity and to open position for removal of a casting therefrom, a pot, .a shot cylinder having a iill-port communicating with the pot, a -gooseneck and nozzle connected with the shot cylinder, a shot plunger in the cylinder means for traveling the plunger from a starting position above the fill-port to close the till-port and force molten metal from the cylinder through the gooseneck land nozzle into the die cavity and for returning the plunger to its starting position: the improvement comprising mechanical stop means for positively arresting the return movement of the plunger before it passes the fill-port and opens the same to the cylinder; and means actuated by the movable die part as an incident to the opening movement of the latter for causing said `stop means to be rendered inoperative to arrest the plunger `and hence permit movement thereof to starting position above the fillport after the die parts have separated.

2. A die casting machine as defined in claim 1 in which said stop means comprises an abutment connected to the plunger and relatively stationary latch means releasably engaging said abutment.

3. A die casting machine as defined in claim 1 in which the means .actuated by the movable die part for causing the stop means to be rendered inoperative comprises mechanical means connecting the movable die part with the stop means.

4. A die casting machine as defined in claim 2 in which said means for causing the stop means to be rendered inoperative comprises a pull rod connected tothe movable die part and the latch means to release the latch from said abutment.

5. A die casting machine as defined in claim 4 in which there are spring means urging the latch means into position to engage the abutment so as to arrest the returning movement of the plunger.

6. A die casting machine as defined in claim 4 in which the latch means is provided with a mass having sufficient weight and so positioned as to urge the latch means into position to engage the abutment and to arrest the returning movement of the plunger.

7. A die casting machine as defined in claim 1 in which the means for causing the stop means to be rendered inoperative comprises electromagnetic means actuated by the movable die part.

8. A die casting machine as defined in claim 2 in which there is electromagnetic means for withdrawing the latch means from engagement with said abutment.

9. A die casting machine as defined in claim 8 in which there is an electric `circuit for energizing said electromagnetic means including a switch which is closed when the movable die part and a casting carried thereby is separated from the fixed die part.

References Cited by the Examiner UNITED STATES PATENTS 3/1914 McRae. 3/1965 Johnson 22-70 

1. IN A DIE CASTING MACHINE HAVING SEPARABLE DIE PARTS AND MEANS OR MOVING SAID DIE PARTS TO CLOSED POSITION TO FORM A DIE CAVITY AND TO OPEN POSITION FOR REMOVAL OF A CASTING THEREFROM, A POT, A SHOT CYLINDER HAVING A FILL-PORT COMMUNICATING WITH THE POT, A GOOSENECK AND NOZZLE CONNECTED WITH THE SHOT CYLINDER, A SHOT PLUNGER IN THE CYLINDER MEANS FOR TRAVELING THE PLUNGER FROM A STARTING POSITION ABOVE THE FILL-PORT TO CLOSE THE FILL-PORT AND FORCE MOLTEN METAL FROM THE CYLINDER THROUGH THE GOOSENECK AND NOZZLE INTO THE DIE CAVITY AND FOR RETURNING THE PLUNGER TO ITS STARTING POSITION: THE IMPROVEMENT COMPRISING MECHANICAL TOP MEANS FOR POSITIVELY ARRESTING THE RETURN MOVEMENT OF THE PLUNGER BEFORE IT PASSES THE FILL-PORT AND OPENS THE SAME TO THE CYLINDER; AND MEANS ACTUATED BY THE MOVABLE DIE PART AS AN INCIDENT TO THE OPENING MOVEMENT OF THE LATTER FOR CAUSING SAID STOP MEANS TO BE RENDERED INOPERATIVE TO ARREST THE PLUNGER AND HENCE PERMIT MOVEMENT THEREOF TO STARTING POSITION ABOVE THE FILLPORT AFTER THE DIE PARTS HAVE SEPARATED. 